Failing to catch a specific error

Question

I wrote this simple code:

#!/usr/bin/python2.7 -tt

import subprocess

def main()
  try:
    process = subprocess.check_output(['unvalidcommand'],shell=True)
  except CalledProcessError:
    print 'there is the calledProcessError'


if __name__ == '__main__':
  main() 

Expected output: there is the calledProcessError

What I got: NameError: global name 'CalledProcessError' is not defined

Answer 1

def main():
  try:
    process = subprocess.check_output(['unvalidcommand'],shell=True)
  except subprocess.CalledProcessError: # need to use subprocess.CalledProcessError
    print 'there is the calledProcessError'
main()
there is the calledProcessError
/bin/sh: 1: unvalidcommand: not found

Or just import what you need from subprocess:

from subprocess import check_output,CalledProcessError

def main():
  try:
    process = check_output(['unvalidcommand'],shell=True)
  except CalledProcessError:
    print 'there is the calledProcessError'
main()

Answer 2

subprocess.CalledProcessError is not a builtin exception. You need to qualify the exception name to use it.

except subprocess.CalledProcessError:
       ^^^^^^^^^^^

or you need to import it explicitly:

from subprocess import CalledProcessError